Mixed problems for singular and degenerate hyperbolic equations (Q1812714)

The author considers a mixed problem for a degenerate hyperbolic equation with principal symbol \(\prod^ m_{j=1}(\tau-t^ k\Lambda_ j(t,x,y;\xi,\eta))\), where \(k\) is a real number, \(k>0\), the variables \((\xi,\eta)\) are dual to \((x,y)\), and the \(\Lambda^ j(t,x,y;\xi,\eta)\) are real and distinct. For this problem the author proves existence and uniqueness of the solution and establishes an energy estimate.